Stinky air, yes; hazardous, no; source, unknown

To those craving a solution to the mystery, this update may stink — about as bad as the air did in the San Diego area two days ago.

Tests on atmospheric samples collected that strangely pungent afternoon pinpointed no cause for the fuel-like chemical odor that permeated the region for hours, the county Air Pollution Control District reported Friday.

More importantly, though, the screenings also turned up no sign that anything hazardous to public health was wafting through communities from Oceanside to Kearny Mesa.

Technicians analyzed samples from two locales beset by the noxious smell, and the measurements — which detect 56 hydrocarbons and 48 types of toxic contaminants — showed only normal, low, background levels,'' according to Bob Kard, director of the county agency.

"In other words, the results were very good news,'' he said. "Nonetheless, we know the odors were out there and bothering people.''

The first reports of the widespread olfactory affront came from Del Mar and Solana Beach early Wednesday afternoon. Over the next six or seven hours, emergency dispatchers received dozens of 911 calls about the phenomenon, first in neighborhoods near the ocean and then throughout much of the San Diego area.

No one reported any ill health effects from whatever was causing the stench.

People described a heavy'' odor that seemedfuel-like in varying degrees, from gasoline to kerosene,'' Kard said. The stink faded over the evening and was gone by Thursday morning.

While trying in vain to locate the origin of the smell, county officials contacted the Navy, Coast Guard, Camp Pendleton, Lindbergh Field and the Federal Aviation Administration, all of which reported that they had no idea what the source of the odor might be.''

Since the particles or fumes to blame for the unpleasant pall were invisible, it is possible they eluded the personnel who collected air samples in Carmel Valley and Del Mar early Wednesday evening, said Mahmood Hossain, chief of monitoring and technical services for the air-pollution control agency.

This plume was colorless, so we couldn't see if we were inside the plume or outside the plume,'' Hossain said.

In the coming days, analysts will map the complaint calls and document wind information in the hopes of locating where the fumes came from, Kard said, though he cautioned that the process could ultimately prove futile'' due to the transitory nature of the acrid odor.